I guess I'll start with a little background. I bought my Miata in February 2016 as my first car. 1990, 106,000 miles, and manual of course. Here's a pic of it parked outside my house that day.

Paint was rough but mechanically it was sound. Over the next 14 months I've upgraded the headlights to Cibies, swapped in a open diff from a '99 after mine blew up, upgraded to a CXRacing radiator, depowered the steering, and just recently did the timing belt myself. Here's how the car sits now.

Most of my upgrades have been from replacing broken parts with something better than OEM, and this is mostly because it was my daily and I couldn't really afford to have it off the road for long periods of time. But about two months ago I snatched up an $800 1990 LS400 off Craigslist as my daily driver. It's sitting at 227,000 miles but I know they're bulletproof.

(I might have a thing about 1990 silver cars.)

So now I can really start working on the Miata and ultimately turbo it. I've spent the last few months researching and I've come up with what I believe to be a fairly comprehensive spreadsheet and plan. Here's a link. Green means I've bought the part, yellow means I'm ready to buy, and red means I need more research. As you can see, I've started to buy parts. So far, I have the turbo, some hardware, and some downpipe parts. I'm still waiting on flanges to come in the mail, and I need to pick up the manifold tubing from Ace.

Once I get all the manifold goodies I'll be able to weld it all up and bolt on the turbo. From there I'll fabricate the downpipe. My plan is to purchase a few "sections" of the build every two weeks, then spend that time adding them to the car. Next will likely come exhaust.

Well, that's it for today, I hope you guys enjoyed seeing this and are looking forward to updates.

Last edited by byerlyfactor; 04-30-2017 at 06:08 PM.
Reason: Formatting

More parts came today and yesterday. Turns out I ordered the wrong exhaust flange for the turbo. This is what I get when I don't read descriptions. I bought a T3 5-bolt for my T25. Doesn't exactly fit. I guess I'll be returning it and buying the right flange with an oval tube transition. On the plus side, I now have some 2" tubing to practice welding on before I actually fab up the downpipe in 3". 2 3" 4' sections also came from summit. My cutoff wheel came for the miter saw (I know it's not the best idea) as well as a m8x1.25 tap set to clean up the holes on the housing.

It's pretty good. I bought it with a CEL on, code read too rich/ too lean. Plugs and wires only cleared it for a while, but it's back. Not exactly a priority since it doesn't affect drivability. Other than that, the a/c doesn't work, and that's about it. It's wonderful to drive in - very isolated.

I made some progress on the manifold today. I've been way too busy during the last week with school and making sure I graduate. Now that's out of the way I should be able to put much more time into the build.

I cut the tees and els to size. A cutoff wheel takes a LONG time and really makes me wish I had a band saw. The fitment wasn't too bad overall. I also beveled the edges so I could get good penetration and cleaned everything up with the flap wheel. I tacked it all together and that's where it is now.

A gap that wide was a little frightening at first but I'm much more confident in myself after the tacks. I guess a root pass will be easier than I expected.
Also, here's how the back looks. It looks like I'll need to do some porting before I'm done.

So all that's left is to backpurge it, weld it all up, then make the cutout for the T2 flange and weld that on. I'd like to accomplish this in a week but we will see.

Do yourself a favor now, get some new weld els and start over. those gaps are going to crack really quickly. There is a good thread going on about the failure of these log type manifolds. starting out with giant gaps to fill is just speeding up the failure. Not being a dick, just trying to prevent you from a lot of wasted work.

Do yourself a favor now, get some new weld els and start over. those gaps are going to crack really quickly. There is a good thread going on about the failure of these log type manifolds. starting out with giant gaps to fill is just speeding up the failure. Not being a dick, just trying to prevent you from a lot of wasted work.

Well the thread about weld el manifold failures is far more about absurdflow low mount styles cracking. I don't think a log has the same sort of forces in the same directions. Saying all that I would definitely get 2 new tee's and make those so they are closer when you weld. When I build my manifolds I try to get everything touching, or at least within a millimeter or two. Building 1.6 manifolds are my least favorite since everything needs to be cut.

I also have just about zero formal welding training, so I don't really know what is proper or good. I just know what I have done for the last 40 some manifolds I have made, and what seems to work well for me.

Well the thread about weld el manifold failures is far more about absurdflow low mount styles cracking. I don't think a log has the same sort of forces in the same directions. Saying all that I would definitely get 2 new tee's and make those so they are closer when you weld. When I build my manifolds I try to get everything touching, or at least within a millimeter or two. Building 1.6 manifolds are my least favorite since everything needs to be cut.

I appreciate the advice, but I think I'll just end up welding across the gap. I know fit up is important for more precise tig work, but from what I understand there generally is a purposeful gap to allow penetration when welding pipe in the field. With pipe this thick, I think this will give me the strongest welds.

I weld, a lot. some gets tested. I can tell you with 100% certainty that the gap is way too big for tig, mig or stick. you are going to introduce huge amounts of stress ( in the 10's of thousands of lbs) in those joints. continue on.